outboard question

New to me 2014 Mercury 60hp 4 stroke motor with 30 hrs total on an 18ft pontoon. I used motor all weekend with no problems. Today when I was taking it to the boat ramp I gave it full throttle and it seemed like the prop or something was slipping. It reved but speed slowed down.This happened three times. I backed off the throttle and took it easy to the ramp with no further problems. I got home and removed the prop and checked the hub. All seemed fine. Could this be some lower unit problem? If it were a lower unit problem would it also slip at slow speed? Or maybe some cavitation thing that might have worked itself out if I had stayed on the throttle. I am going to take it back out and try it. But, wanted opinions. Thanks.

if the prop and hub are one piece, its likely a spun hub.
the two piece hub/prop combos slide apart when taken off the shaft, the one piece does not.
check by placing a mark on both center hub and shaft nut and back trailer into the water and run in gear, if the lines don't match, you have a spun hub.
Generally about a $60 fix if you have a prop shop in town.
Worth the cost if it's a SS prop, about 1/2 the cost if AL.

Thanks, I will do that. Its a 2 piece and teeth look fine.

two piece? Remove the core from the prop and inspect inner metal part for any deformation at the rubber. If you know the manufacturer, go ahead and order a new hub, and maybe a spare for later.

Teeth rarely get damaged, its the bond between the metal core and rubber that fails.
Don't forget to smear some marine grease on the shaft when putting the prop on every. single. time.

If you don't have a prop wrench in your kit onboard, it would be wise to order one with hub(s). Get a spare cotter pin also.
I know firsthand how bad it sucks to be several miles from the ramp when you spin a hub and have no spare.. not fun.

Could it have been caveating?

I expect that you had a little more weight upfront than normal causing the rear to get less bite thus cavitating. An outboard set to high will do this sometimes

All 2014 merc's (40 hp and up)use a hub kit and prop. The likelihood of having stripped a modern plastic hub is very low, especially if all you were doing was advancing the throttle. If you pull the prop, the hub should easily pull out of the prop. If the hub will not freely fall out of the prop when inverted, gently tap the hub out of the prop using a non matellic tool and inspect the hub, does it appear rolled? If so, replace it, if not, reassemble and turn your attention to possible cavitation issues. Is the cavitation plate on the engine level with the bottom of the motor pod? It should be flush to 1" lower than the bottom of the pod. was there a weight distribution issue when your experienced the lose of speed? Was engine trim proper? Do you have the right size and type prop on the pontoon,? A regular boat prop will not perform well on a pontoon. You must have a big ear'ed pontoon type prop (go to mercury prop calculator web site for size prop for your pontoon setup) typically a 11 or 13 pitch prop is req'ed for most pontoon motors. Outboard height and trim are also sensitive issues with most pontoons and the slightest amount out can introduce cavitation (prop slippage) at certain throttle settings. If the hub is damage free, I suggest you water test the toon again and note if any of the things discussed were contributors to the prop slip.

Thanks for all the help. I think it was cavitation. I did not see any rounding of teeth after removing prop and hub. I might have had motor trimmed high because I had just come out of shallow water. It does have the proper prop setup with 11 pitch and cavitation plate is right at bottom of motor pod. I am going to water test this week and give update. Does the prop actually slip during cavitation or does it just seem like it? One other question about this motor: It won't trim up while moving faster than idle speed. Is that normal?

I agree it sounds more like a cavitation issue. All props slip a little, ideally the more water around a prop the better it performs and yes if air (cavitation) gets around your prop it will lose its grip and begin to slip. The most noticeable effect is a sudden lost of power (thrust) and a increase of RPM. I failed to mention yesterday, most pontoon boats plow thought the water, and do not plane out like a regular boat , so most pontoon boat motors require a heavily cupped prop to minimize slippage (the exception is those pontoons with lifting stakes and large HP engines). Make a point to check the trailing edge of your props blades for a distinct cupped edge. As for the trim issue you mentioned, your engine should trim (but not tilt) while under power at all throttle settings. Check to ensure the hydraulic reservoir on the tilt/trim unit is full, if its low this could be the reason your engine isn't trimming while under power. Good luck and let us know how it does.